The neostriatum and other basal ganglia nuclei play a role in the etiology of several neurological disorders including Parkinson's disease, Huntington's chorea, Tourette's syndrome, and schizophrenia. To understand how the neostriatum processes information from the cerebral cortex, we will study the topography of corticostriatal connections and their relationship to the coordination of neostriatal activity. Specific Aim 1. To determine the precise topographic organization of corticostriatal projections from somatosensory areas that process functionally-related information. We hypothesize that cortical areas that are activated conjointly or in close temporal sequence during behavior are more likely to project to overlapping neostriatal regions than cortical areas that are not coactivated during somesthesis-guided behaviors. To test this hypothesis, we will reconstruct anterogradely-labeled corticostriatal terminals originating from different parts of primary (SI) and secondary (SII) somatosensory cortex. Specific Aim 2. To determine if neostriatal neurons within the sensorimotor channels are functionally coupled and to elucidate some of the rules governing their coordination. We hypothesize that groups of neostriatal neurons are coordinated by the corticostriatal pathways, and that this coordination is governed by the organization and temporal sequence of activity in those pathways. To test this hypothesis, we will record multiple neostriatal neurons during spontaneous and stimulus-induced activity. Cross-correlation analysis will be used to characterize changes in the response patterns of neostriatal neurons with respect to the pattern of peripheral stimulation.